The present invention relates to electrostatic powder painting apparatus.
As is well known, with such an apparatus it is possible to electrostatically charge paint in powder form so that it will become deposited on a surface which is to be painted.
With conventional electrostatic powder painting apparatus, the powder paint is supplied from a storage tank to be pneumatically conveyed to a powder gun provided with a corona discharge electrode having a high DC voltage applied thereto, so that the powder paint is charged by unipolar ions to be driven and deposited electrically onto the surface of an object which is to be painted and which is positioned in front of the powder gun. With conventional apparatus of this type there is a serious disadvantage in that the total amount of air, supplied by a compressor or blower for pneumatically conveying the powder, is discharged from the outlet of the powder gun together with the powder. This total amount of air which is discharged with the powder hinders the flow of the powder paint due to the electrostatic charging thereof and lowers the painting efficiency. If, in order to alleviate this drawback, it is attempted to decrease the amount of air, then the smooth pneumatic conveying of the powder paint is prevented, and the conveyed air pulsates undesirably so as to result in a non-uniform supply as well as non-uniform charging, thus unavoidably reducing the painting efficiency and the quality of the painting.